Guitar string tuning machine



FIG. 1 is a top plan view of a guitar string tuning machine showing mynew design;

FIG. 2 is a front elevational view;

FIG. 3 is a bottom plan view;

FIG. 4 is a left side elevational view;

FIG. 5 is a right side elevational view; and

FIG. 6 is a rear elevational view.

The ornamental design for guitar string tuning machine, substantially asshown.